Such an adjusting device has already been described in Austrian Pat. No. 350 499. A locking member of this adjusting device is under the influence of a pressure spring, which urges the teeth of the locking member into serrations provided in an edge of an elongated strip; thus the locking is frictional. Since the teeth have generally, in a top view, the design of isosceles triangles, it can happen that the pressure onto the binding part is too great so that the force of the pressure spring is overcome and the locking member is moved along the serrations, which results in damage to the teeth both on the locking member and also to the serrations on the strip.
The purpose of the invention is to overcome this disadvantage and to provide an adjusting device in which the locking of the teeth on the locking member occurs through a positive form locking device.
This purpose is inventively attained by the provision of a locking member which is fixed by a force-locking arrangement in the locked condition by an intermediate member, so that an unintended opening of the adjusting device is not possible.
A slight deformation of the intermediate member is made possible by making the intermediate member of spring-steel wire, which makes the operation easier.
A split design of the locking member is not absolutely necessary for the proper functioning of the adjusting device. Of course, a nonsplit design assumes a substantially generous play between the locking member and the carriage, which at times is undesired. The amount of play can be reduced considerably when an axle joint is provided on the locking member, since the area of the locking member, which area carries the locking teeth, is no longer being swivelled, but is only being moved.